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From: Jason Gunthorpe <jgg@nvidia.com>
To: Lu Baolu <baolu.lu@linux.intel.com>
Cc: Joerg Roedel <joro@8bytes.org>, Will Deacon <will@kernel.org>,
	Robin Murphy <robin.murphy@arm.com>,
	Kevin Tian <kevin.tian@intel.com>,
	Dmytro Maluka <dmaluka@chromium.org>,
	Samiullah Khawaja <skhawaja@google.com>,
	iommu@lists.linux.dev, linux-kernel@vger.kernel.org
Subject: Re: [PATCH v2 0/3] iommu/vt-d: Ensure atomicity in context and PASID entry updates
Date: Tue, 20 Jan 2026 09:56:54 -0400	[thread overview]
Message-ID: <20260120135654.GB1134360@nvidia.com> (raw)
In-Reply-To: <20260120061816.2132558-1-baolu.lu@linux.intel.com>

On Tue, Jan 20, 2026 at 02:18:11PM +0800, Lu Baolu wrote:
> This is a follow-up from recent discussions in the iommu community
> mailing list [1] [2] regarding potential race conditions in table
> entry updates.
> 
> The Intel VT-d hardware fetches translation table entries (context
> entries and PASID entries) in 128-bit (16-byte) chunks. Currently, the
> Linux driver often updates these entries using multiple 64-bit writes.
> This creates a race condition where the IOMMU hardware may fetch a
> "torn" entry — a mixture of old and new data — during a CPU update. This
> can lead to unpredictable hardware behavior, spurious faults, or system
> instability.
> 
> This addresses these atomicity issues by following the translation table
> entry ownership handshake protocal recommended by the VT-d specification.

This seems like a reasonable first series

Thanks,
Jason

      parent reply	other threads:[~2026-01-20 13:56 UTC|newest]

Thread overview: 17+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2026-01-20  6:18 [PATCH v2 0/3] iommu/vt-d: Ensure atomicity in context and PASID entry updates Lu Baolu
2026-01-20  6:18 ` [PATCH v2 1/3] iommu/vt-d: Clear Present bit before tearing down PASID entry Lu Baolu
2026-01-20 13:56   ` Dmytro Maluka
2026-01-20 18:14     ` Samiullah Khawaja
2026-01-21  6:16   ` Tian, Kevin
2026-01-20  6:18 ` [PATCH v2 2/3] iommu/vt-d: Clear Present bit before tearing down context entry Lu Baolu
2026-01-20 14:07   ` Dmytro Maluka
2026-01-20 18:22   ` Samiullah Khawaja
2026-01-21  6:23   ` Tian, Kevin
2026-01-21  7:28     ` Baolu Lu
2026-01-21  7:50       ` Tian, Kevin
2026-01-21  8:04         ` Baolu Lu
2026-01-21  8:12           ` Tian, Kevin
2026-01-20  6:18 ` [PATCH v2 3/3] iommu/vt-d: Fix race condition during PASID entry replacement Lu Baolu
2026-01-20 18:54   ` Samiullah Khawaja
2026-01-21  6:23   ` Tian, Kevin
2026-01-20 13:56 ` Jason Gunthorpe [this message]

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